Black Henna explained
Health authorities in many countries warn against black henna. A reaction may not appear on the first use but can be triggered on later exposure, including to hair dye.
Real henna is never black on the skin. It starts orange and deepens to reddish-brown. Jagua, a plant-based dye, can give a blue-black stain, but it is a different product altogether.
Also searched as: kala mehendi · black mehendi · black henna danger